The present invention relates to a thin film magnetic head, in which magnetic resistance (MR) element sections are formed on an insulating layer formed on a surface of a magnetizable metal substrate, and a method of manufacturing the thin film magnetic head.
Thin film magnetic heads for reproducing data, each of which includes magnetic resistance element sections for reproducing data, which are formed on an insulating layer formed on a surface of a magnetizable substrate, are assembled in magnetic tape memory devices.
A conventional thin film magnetic head, which is a separate type magnetic head assembled in a magnetic tape memory device, is shown in FIG. 6. FIG. 6 is an explanation view showing a summarized structure of the head. The separate type magnetic head has a magnetic resistance element section 10 for reproducing data (hereinafter referred to as xe2x80x9creproducing head sectionxe2x80x9d) and a magnetic resistance element section 12 for writing data (hereinafter referred to as xe2x80x9cwriting head sectionxe2x80x9d), which are arranged side by side, on a surface of a magnetizable substrate 14 (e.g., Nixe2x80x94Zn-Ferrite substrate) for shielding a lower part, with a proper separation. In FIG. 6, one reproducing head section 10 and one writing head section 12 are shown, but many reproducing head sections 10 and many writing head sections 12 are formed on the magnetizable substrate 14 of the actual magnetic head.
Firstly, the reproducing head section 10 will be explained.
The head sections 10 and 12 are formed on the magnetizable substrate 14, and the substrate 14 acts as a lower shielding layer of the reproducing head section 10.
A first insulating layer 16, which is made of a non-magnetizable GAP material (e.g., alumina), is formed on the surface of the magnetizable substrate 14. The first insulating layer 16 acts as a half-GAP.
An MR element section 18 (e.g., SAL/Ta/MR type) is formed on a surface of the first insulating layer 16.
A pair of Coxe2x80x94Crxe2x80x94Pt/MR terminals 20 (hereinafter referred to as xe2x80x9cMR terminalsxe2x80x9d) are respectively provided on both sides of the MR element section 18.
A second insulating layer 22, which is made of a non-magnetizable GAP material (e.g., alumina), is formed on the surface of the first insulating layer 16 so as to cover over the MR element section 18 and the MR terminals 20.
Namely, the MR element section 18 and the MR terminals 20 are sandwiched between the two insulating layers 16 and 22. The second insulating layer 22 acts as an insulating film of an upper shielding layer 24 and the half-GAP.
An upper shielding layer 24, which is made of a soft magnetic metal film, is formed on a surface of the second insulating layer 22.
A protection layer 26 is formed on a surface of the upper shielding layer 24.
Next, the writing head section 12 will be explained.
The magnetizable substrate 14 supplements a lower magnetic pole 28.
The lower magnetic pole 28, which is a soft magnetic metal film, is formed on the surface of the magnetizable substrate 14.
A write-GAP 30 is made of a non-magnetizable GAP material (e.g., alumina).
An upper magnetic pole 32, which is a soft magnetic metal film, is formed on a surface of the write-GAP 30.
The protection layer 26 is formed on a surface of the upper magnetic pole 32.
The Nixe2x80x94Zn-Ferrite substrate is employed as the magnetizable substrate 14, on which the reproducing head section 10 and the writing head section 12 are formed, by following reasons.
Firstly, the Nixe2x80x94Zn-Ferrite material is a stable oxide which has superior magnetic property (e.g., greater specific resistance) and superior high frequency property. Secondly, the Nixe2x80x94Zn-Ferrite material has greater hardness, so it is a proper material to contact a magnetic tape, which is pressed there onto with high contact pressure. Namely, the Nixe2x80x94Zn-Ferrite material has superior tape-touch property and tape-slide property. Thirdly, the Nixe2x80x94Zn-Ferrite material has high reliability and superior records of employment. Besides the head of the magnetic tape memory device, magnetic heads employing the Nixe2x80x94Zn-Ferrite substrates have been assembled in heads for flexible memory media (e.g., VTR tapes, flexible disks).
However, the Nixe2x80x94Zn-Ferrite substrate has following disadvantages.
These days, required memory density of the magnetic tape memory is higher and higher, so that the first insulating layer 16 and the second insulating layer 22 of the reproducing head section 10 must be thinner.
But the Nixe2x80x94Zn-Ferrite material is a sintered material, so a large number of fine holes 34 (see FIG. 7) are formed therein. With this structure, the fine holes 34 are opened in the surface of the magnetizable substrate 14 when the surface of the magnetizable substrate 14 is abraded. In FIG. 7, the fine hole 34 is opened in the surface of the magnetizable substrate 14. The fine hole 34 is a hollow hole and formed by a HIP manner. A maximum diameter of the fine hole 34 is about 5 xcexcm.
If the first insulating layer 16, the MR element section 18 and the second insulating layer 22 are directly formed on the surface of the magnetizable substrate 14, in which the fine holes 24 are opened, by sputtering, the films 16, 18 and 22 fall into the fine holes 34. Therefore, the films 16, 18 and 22 are partially depressed, so that thickness of the films 16, 18 and 22 are made partially thinner.
If the first insulating layer 16 and the second insulating layer 22 are made thinner so as to make the memory density of the magnetic tape memory higher, the thickness of the films 16, 18 and 22 are made further partially thinner. By making the thin insulating layers 16 and 22 further partially thinner, enough insulating strength cannot be gained between the upper shielding layer 24 and the MR element section 18, so that number of bad products, whose insulating strength are lower than a prescribed strength, must be increased.
An object of the present invention is to provide a thin film magnetic head, in which insulating layers and an MR element having uniform thickness can be formed on a surface of a magnetizable substrate, which includes fine holes, with enough insulating strength. Another object of the present invention is to provide a method of manufacturing said thin film magnetic head.
To achieve the objects, the thin film magnetic head of the present invention comprises: a magnetizable substrate; a magnetizable metal layer being formed on a surface of the magnetizable substrate; a first insulating layer being formed on a surface of the magnetizable metal layer; a magnetic resistance effect (MR) element section for reproducing data being formed on a surface of the first insulating layer; a second insulating layer being formed on the magnetic resistance element section so as to sandwich the magnetic resistance element section between the first insulating layer and the second insulating layer; and a shielding layer being formed on a surface of the second insulating layer.
With this structure, the insulating layers and the MR element section are formed on the flat surface of the magnetizable metal layer, which has been formed on the magnetizable substrate, so that the insulating layers and the MR element section are not partially depressed even if fine holes are formed in the surface of the magnetizable substrate. Unlike the conventional magnetic head in which the insulating layers and the MR element section are directly formed on the uneven surface of the magnetizable substrate, the thickness of the insulating layers and the MR element section of the magnetic head of the present invention can be uniform. Therefore, the insulating strength of the MR element section can be improved, and number of the bad products, whose insulating strength are lower than the prescribed strength, can be reduced.
Another thin film magnetic head of the present invention comprises: a thin film magnetic head section for reproducing data; and another thin film magnetic head section for writing data, wherein the thin film magnetic head section for reproducing data includes said thin film magnetic head.
The method of the present invention comprises the steps of: forming a magnetizable metal layer on a surface of a magnetizable substrate; abrading a surface of the magnetizable metal layer so as to make the surface flat; forming a first insulating layer on the surface of the magnetizable metal layer; forming a magnetic resistance effect (MR) element section for reproducing data on a surface of the first insulating layer; forming a second insulating layer on the magnetic resistance element section so as to sandwich the magnetic resistance element section between the first insulating layer and the second insulating layer; and forming a shielding layer a surface of the second insulating layer.
In the method, the magnetizable metal layer may be made of a soft magnetic metal. With this method, the magnetizable substrate is also made of the soft magnetic metal, so the magnetizable metal layer and the magnetizable substrate have the same magnetic property and shielding property.
The soft magnetic metal has greater abrasion resistance, corrosion resistance, etc. Further, a surface of the soft magnetic metal can be easily abraded so as to make the flat mirror face. Especially, even if the surface is abraded by chemical-mechanical polishing, the soft magnetic properly is not badly influenced. Fexe2x80x94Alxe2x80x94Si, Fexe2x80x94N, Fexe2x80x94Sixe2x80x94N, Coxe2x80x94Zrxe2x80x94Nb, etc. may be employed as the soft magnetic metal, which has the greater abrasion resistance and whose magnetic property can be easily controlled.
In the method, the chemical-mechanical polishing may be executed in the abrading step so as to make the surface of the magnetizable metal layer flat and smooth like a mirror face.